Heating of thermite charge: Influence on structure and properties of Fe–Al-based intermetallic alloy ingot produced by exothermic melting

The high resistance of iron–aluminum intermetallic alloys to abrasive wear and corrosion in aggressive environments underscores their significance in mechanical engineering and electrical applications. In metallurgy, these alloys are extensively used as alloying additions. The production of such alloys and coatings typically involves multiple sequential operations and significant energy consumption. However, the aluminothermic process occurring in thermite compositions consisting of mill scale and aluminum alloy swarf has the potential to reduce the number of production steps. The elevated temperatures and reduced interaction duration between aluminum and iron in the liquid phase ensure an increased aluminum content in the resulting alloy. This study established the feasibility of preheating thermite mixtures, containing 20–24% active aluminum, prior to activating the aluminothermic process. The objective was to achieve a more stable chemical composition of the final product and reduce porosity in the ingot while maintaining satisfactory metallic yield. The experimental results demonstrate the influence of thermite preheating and the content of active aluminum on combustion rate, metallic yield, aluminum content, and the structure and microhardness of the iron–aluminum alloy formed by aluminothermy in a graphite reactor.